Authors

Document Type

Journal/Book Title/Conference

Volume

11

Issue

6

First Page

1656

Last Page

1666

Publication Date

2001

Abstract

Retention of residual trees in ‘‘cutblocks,’’ logged blocks of forest, has been proposed as a method to conserve songbirds in landscapes fragmented by clear-cut logging. We examined songbird communities in the boreal mixed-wood forest of Alberta, Canada, to investigate the effect on songbird abundance of (1) logging and (2) retaining variable densities of residual trees in cutblocks (10–133 trees/ha or basal area of 0.50–10.65 m2). We surveyed songbirds in logged and forested, aspen-dominated, mixed-wood stands in the year before, the year after, and three years after logging. We analyzed changes in abundance of 27 common songbird species: 23 present in the forest prior to logging and four that appeared after logging. Ten species declined with logging and were termed ‘‘forest species.’’ Ten more species did not change with logging and were called ‘‘habitat gener- alists.’’ The seven species that increased with logging were called ‘‘cutblock species.’’ When the effect of residual tree retention was examined in terms of basal area (rather than density) of residual trees, more songbird species were found to be both positively and negatively affected by residual tree retention, despite the fact that the two tree measures were highly correlated. In the first year after logging, four bird species (two forest, one generalist, and one cutblock) increased, and none decreased with increasing residual tree retention in cutblocks. In the third year after logging, again four species increased with increasing retention, but these were different species than in the first year after logging (one forest and three generalist species). Furthermore, four cutblock species decreased with increasing retention. Based on these findings, we conclude that retention of residual trees may be beneficial to some species, although conservation of unlogged reserves is also important. Most importantly, we recommend that research be continued to examine a larger range of tree retention and longer term effects on the avifauna.